Warehouses can be automated through the use of AGVs that facilitate the transportation of materials. Such vehicles are often computer controlled to deliver materials between designated locations. The vehicles can navigate by following a wire embedded in the ground which emits a radio frequency signal on which the vehicles can be moved between fixed areas (load/unload stations) on a fixed route. However, it is more desirable to have vehicles with flexible, alternate routes which enable the vehicles to be routed around obstacles, such as stopped AGVs, avoid stopping for cross traffic, and travel minimum distance routes between two given points. A subclass of AGVs includes autonomous self guided vehicles which have sophisticated on board controls and computers, which allow these vehicles to be free ranging.
The flexible route to be taken by the autonomous vehicles can be so designated by several methods. One such method incorporates bar codes in conjunction with lasers that scan the bar codes. The vehicles contain a laser which scans bar codes contained on objects designated as reference points and thereby determines their location relative the object. The corresponding route to reach a destination can be calculated by a computer. The vehicles may be any of a wide variety of different types, but one such vehicle is that known as a "Self-Guided Vehicle" (SGV) from Caterpillar Industrial Inc.
Additional systems are also available which use still other means of achieving autonomous guidance that may be suitable for a given application. Such systems may utilize sonar, infra-red vision, ultrasound, electromagnetics, dead-reckoning utilizing encoders, grid-calibration, transponders and on-board cameras. Suppliers for these systems include Cybermotion, Denning Mobile Robotics, Inc., Flexible Manufacturing Systems, Inc. and Frog Systems, Inc.
An industrial truck is usually not well suited for use in loading/unloading materials onto and off of autonomous AGVs. Autonomous AGVs are inherently expensive and often contain fragile computerized control equipment and sensors which render the vehicles particularly vulnerable to damage from industrial trucks. Therefore, materials are usually loaded onto and removed from autonomous AGVs at fixed load/unload conveyor stations.
Accordingly, it would be desirable to provide a portable docking apparatus as an alternative interface to the large scale material handling trucks whereby material can be safely loaded and unloaded at variable locations and be more conveniently accessible to a greater number of autonomous AGVs.
Portability is desirable in order to free up the floor area when loading/unloading is not needed in that particular location. Relatively few portable load/unload modules would be needed since these modules would be efficiently used. The autonomous AGVs would travel shorter distances overall when loaded, and would travel loaded a significantly greater percentage of time. Therefore, a portable docking apparatus would minimize idle facilities and reduce resulting capital investments.
These portable modules would need to be sturdy and capable of withstanding heavy impacting by large trucks and the like. There also needs to be a coordinated sensory system through which the autonomous AGVs are able to locate a module which is portable and, therefore, does not have a fixed location. Since the docking module is intended for use with the manned industrial trucks it is likely that trucks will collide with the module and occasionally alter its position. The autonomous AGVs need to be able to locate a docking module that has had its position altered slightly through the impact force of a truck while loading or unloading material. Therefore, it is important that the AGVs locate the docking module by detecting its position and not by relying on where the module should be stationed.
The current invention overcomes one or more of the foregoing problems and accomplishes one or more of the aforementioned objectives.